roles/php-fpm: Fix Ansible template parsing issue

Remove time formatting strings because Ansible errors when trying
to parse them, even though we are not using them!

roles/php-fpm/templates/php7.3-pool.conf.j2

@@ -306,14 +306,10 @@ pm.max_spare_servers = 3
 ;  %s: status (response code)
 ;  %t: server time the request was received
 ;      it can accept a strftime(3) format:
-;      %d/%b/%Y:%H:%M:%S %z (default)
 ;      The strftime(3) format must be encapsuled in a %{<strftime_format>}t tag
-;      e.g. for a ISO8601 formatted timestring, use: %{%Y-%m-%dT%H:%M:%S%z}t
 ;  %T: time the log has been written (the request has finished)
 ;      it can accept a strftime(3) format:
-;      %d/%b/%Y:%H:%M:%S %z (default)
 ;      The strftime(3) format must be encapsuled in a %{<strftime_format>}t tag
-;      e.g. for a ISO8601 formatted timestring, use: %{%Y-%m-%dT%H:%M:%S%z}t
 ;  %u: remote user
 ;
 ; Default: "%R - %u %t \"%m %r\" %s"